Yüksek Hızlı Tren or YHT (English: High Speed Train) is a high-speed rail service operated by TCDD Transport in Turkey.

As of 2025, the network spans 1,385 km (860.6 mi) and serves major cities like Istanbul, Ankara, Eskişehir, İzmit, Konya, and Sivas.

In Istanbul, YHT trains use the Marmaray Tunnel to traverse the Bosphorus Strait and reach the European side of the city.

On 30 March 2007, TCDD signed an agreement with Trenitalia of Ferrovie dello Stato to rent an ETR 500 train set for 4 months for testing the system.

[6][7] The first run was from Haydarpaşa Terminal in Istanbul to the Central Station in Ankara, using the completed portion of the high-speed line between Hasanbey and Esenkent.

[10] The Transportation Ministry spent 14 million TL (around 7 million Euros at that time) for the installation of testing and measuring equipment on the train, which it named – because it is a tradition to give a name to test trains – as "Piri Reis" after the renowned Turkish admiral and cartographer who drew some of the most accurate and detailed maps of the Mediterranean Sea and the Americas in the early 16th century.

Out of over 100 entries, the ones with the highest votes were: Türk Yıldızı (Turkish Star), Turkuaz (Turquoise), Yüksek Hızlı Tren (High Speed Train), Çelik Kanat (Steel Wing) and Yıldırım (Lightning).

The Marmaray project, which consists of a rail transport network around Istanbul and the world's deepest immersed tube railway tunnel under the Bosphorus strait, is also under construction.

Additionally, new stations are to be constructed in İstanbul, Izmir, Edirne, Trabzon, Erzurum, Erzincan, Sivas, Kayseri, Antalya, Afyon, and Polatlı.

But the YHT also runs on non-high-speed and renewed tracks like the Köseköy-Gebze section of the Ankara–Istanbul high-speed railway where its top speed is 160 km/h (99 mph).

Naturally, some speed restrictions also apply in urban sections while accessing the central station, especially in Ankara and Istanbul thus increasing journey times.

The speed on these sections is expected to increase once renewal projects in urban areas (like Başkentray and second phase of Marmaray) are completed.